Synchronous dynamo-electric machine



Oct. 16, 1923. 1,470,939

SYNCHRONOUS DYNAMO ELECTRIC MACHINE Filed May 29 1919 2 Sheets-Sheet 1INVENTOR ATTORNEY Oct. 16, 1923.

H. SHO

SYNCHRONOUS DYNAMO ELECTRIU MACHINE 2 Sheets-Sheet 2 Filed May 29, 1919filforney peril Patented Oct. 16,- 1923.

lumrao STATES HITOBI 8110, OF NIBIKABUGAI GUN, JAPAN.

, mcnaonous mmaxo-anac'rarc mm 'Applloation me lay as,

To all whom it may concern: I

Beit known that Hnosl S lo, a subigct of the Emperorof apan residing ato. Simpukuji, Syonai -Mura, Nisikasugai Gun, Prefecture of Aichi, in theEmpire of Japan, have invented certain new and useful Improvements inSynchronous Dynamo- Electric Machines, of which the following is a scification. y

is invention relates to s nchronous dynamo-electric machines, and as forits primary object to produce a machine which opcrates with highefficiency and without sparking, either as a synchronous motor or as aconverter of alternating into direct currents.

The machine according to the present invention is composed of twoprincipal parts, namely, a transformer and a motor. The construction ofthe transformer may be of any type adapted to produce a rotary potentialaround a commutator by means of the primary polyphase alternatingcurrent. I

In one embodiment of the invention the transformer comprises a primarypqlyphase winding, a secondary winding arranged in" the rota fieldproduced by the said primary an a, commutator connected electrically tothe said secondary, while the motor is an induction motor having thesame number of poles as that of the transformer primary windin on thesaid commutator, and also provid with one or more windlngs on its rotor,preferably the same number of windings as that'of the oles, one or more(the same number as t c said windings) pairs of brushes bearin on thecommutator and fixed to the sai rotor, the brushes of each pair arrangedwith a small phase difference apart, electrical connections between thepairs of brushes and the rotor windings respectively, and means formaintainin relative rotation at -s chronous speed tween the brushes andt e commutator.

In order that the invention. may be fully understood a preferredembodiment thereof will now be described in the accompanying drawings inwhich:

Fig. 1 i a diagram showing the potential distribution around thecommutator by means of broken lines;

2 and 3 show the disposition of the brushes relative to the potentialand the potential difierences between difierent brushes;

F 1g. 4 is a diagrammatic showing of the 1918. Serial No. 800,887.

1g. 6 is a diagram showing another ary rangement of the machine. a

In Figs. 4and 5, A denotes the-primary windings, which are adapted toreceive polyphase current. In the example illustrated the primary hasthree hases and one pair of poles per phase, but t ere need not be anydistinct pole pieces, it being necessary only that the primary coils pbe arranged to create a rotary magnetic field. The secondary windings sare wound like the armature of a direct current generator, beingconnected to the commutator B, which is fixed. Two pairs of brushes. (aa and (6 b,) are arranged to rotate in contact with the commutator, thecorresponding brushes of each pair making contact with preferably con;secutive commutator segments as clearly shown in Fig. 1, or at least insuch a manner as to give a small difference. in phase between the twosets of brushes. The brushes are rotated by means of a small inductionmotor C of the squirrel cage type, fed from the same polyphase circuitas the primary 2. The rotor of the induction motor has two coils a Q theterminals ((1 a?) and (b b) of which are connected electrically to thebrushes (a a and (b 1),) respectively.

Fig. 5 shows the machine designed as a converter. (1 and b are the sliprings connected electrically to the brushes (a 6 or 'to the brushes (a11,) or to a third pair of brushes also consecutivel arranged on thecommutator and rotate similarl to the other brushes (as at Fig. 6).Direct current is delivered b primary p and til and the wholetransformer iently be placed in an oil tank.

Fig. 6 shows diagrammatically the machine designed as a converter, thisfigure showing the transformer constructed as an auto-transformer, theslip rings a, 12 bein connected to a third set of brushes placed midwaybetween the brushes 0, and 11 -6 This third set of brushes carnesthemain current of the converter through the said slip rings.

Thechief obstacles to commutating a rotary potential is that thepotential difi'ere secondary a are fixed, can conven the slip rings.Both the Where once in the secondary circuit depends u on the variablephase of the rotating brus es, and 'that the secondary current isvariable; when the phase of contact between the brushes and thecommutator is not coincident with the maximum or the minimum of therotating potential at the commutator B, there will be sparking.

The machine of this invention is free from this objection because theangular position of the rotor is determined by the an gular lposition ofmaximum or minimum potentia at the commutator exce t for a negligiblelag due to friction, an the brushes phase with each othei'.

a When rating as a converter the efliciency of t e machine is as high asthat of a and the commutator potential are always in 1=The moment ofinertia of the rotary bod U=The torque per unit slip velocity. E=Themaximum potential on commu- I 4 tater (B) muiti lied by the sine of thehalf angle between t s consecutive brushes. =The flux multiplied by thenumber of turns of the coil or or {5.

rzThe resistance of the coil or or B.

F=The frictional torque.

u=The hase difference between the bisector of t e angle between theconsecutive brushes, and the line of maximum potential.

=The phase difierence between the maximum potential and the rotatingfield.

By a proper design,,the motlon can be defined by the solution '2 and 3.These potential differences create good transformer, and the movingparts are very small and light while no excitin current is neoessa erotor has to overcome only smal frictional resistances and the" motorlosses are small.

Synchronism is maintained owin potential difl'erences which arise thebrushes a3 and a, and between the brushes b, an b, when the base of thebrushes is not coincident with t 0 maximum or the minimum potential, asshown in Figs.

to the tween a curnent in the windings a and B which automaticallyregulates the machine.

The motion of the synchronous motor and of the converter is given by thedifferential equation:

lila pair of slip rings mounted on the rotor 80 aft of said motor, andfrom which slip rings seconda direct current is led out, one of thepairs 0 said brushes being connected to the said slip rings.

3. In a converting apparatus as in claim 85 1, a third pair of brushesslightly displaced fromthe said two pairs of brushes, and also designedto cooperate with said commutator, a pair of slip rings, mounted on therotor shaft of the said motor which are connected to to the said thirdpair oi brushes, from which slip rings secondary direct current is ledout.

4. In a converting apparatus as in claim 1, additional windings on therotor of the said motor, adapted to regulate the motion 95 of the saidrotor, by assisting the other windings.

In testimony whereof I ailix my signature in presence of two witnesses.

HITOSI SIIO.

Witnesses:

Wm. B. Lsxooox, S. Hoanrn.

